Carbon Dosing Biopellets Reef Guide: NO3 and PO4 Reduction
Bacteria drive more of reef chemistry than most hobbyists realise, and carbon dosing is simply feeding them a sugar source so they outcompete algae for nutrients. This carbon dosing biopellets reef guide from Gensou Aquascaping at 5 Everton Park covers the three main approaches – vodka, vinegar and solid biopellets – along with the ramp schedules and failure modes we see most often in Singapore tanks running heavy feeding loads.
How Carbon Dosing Works
Heterotrophic bacteria consume organic carbon and incorporate nitrate and phosphate into their cell mass in a roughly 106:16:1 ratio. A protein skimmer then exports those bacteria as foam. Dose too much carbon and bacteria strip nutrients below plant-tissue needs; dose too little and you feed cyanobacteria instead.
Vodka Dosing
Plain vodka at 40% ABV is the traditional carbon source. Start at 0.1 ml per 100 litres daily and increase by 10% weekly until nitrate drops into the 2-5 ppm range. Expect noticeable export within 3-4 weeks. Vodka is clean, shelf-stable, and easy to pump but evaporates if your dosing reservoir is open.
Vinegar Dosing
White vinegar contains roughly one-tenth the carbon density of vodka, so doses are proportionally larger. Start at 1 ml per 100 litres daily. The lower potency makes vinegar more forgiving for new carbon dosers and friendlier when combined with Kalkwasser because it has a mild pH-lowering effect that balances the hydroxide. Our balling method reef dosing guide explains how vinegar slots alongside Balling.
Biopellets
NP biopellets are solid polymer beads, usually PHA, that tumble in a reactor. Bacteria colonise the surface and consume the plastic slowly while exporting nitrate and phosphate. A typical dosage is 80-100 ml of pellets per 100 litres of tank water. Pellets eliminate the dosing pump entirely but need a fluidised reactor and a skimmer outlet within 30 cm of the reactor discharge to catch freed bacteria.
Combined Approaches
Many Singapore reefers run biopellets as a constant base with small vinegar doses to fine-tune. This hybrid works well on mixed reefs with variable feeding. Avoid stacking vodka and biopellets together – the bacterial bloom risk climbs sharply and cyanobacteria often follows. Pair carbon dosing with our gfo vs phosban phosphate removal approach because phosphate usually falls slower than nitrate.
Target Levels
Aim for nitrate 2-8 ppm and phosphate 0.03-0.08 ppm. Driving either to zero causes pale corals, dinoflagellate outbreaks and loss of colour saturation. The Redfield ratio matters – if nitrate crashes while phosphate lingers, slow carbon dosing and increase GFO, not the other way around.
Ramp Schedule
Weeks 1-2: baseline dose, no changes. Weeks 3-6: test nitrate weekly, increase dose 10% if levels stay above 10 ppm. Week 7 onwards: hold the dose steady and monitor. Most tanks stabilise between weeks 8 and 12. Rushing the ramp produces bacterial blooms that clog skimmers and starve corals of food.
Bacterial Blooms
Cloudy water in week two of dosing usually means the ramp was too aggressive. Cut the dose by half, increase skimmer wet-skimming until the water clears, and resume the ramp after a week. Persistent cloudiness combined with trailing bacterial strands on rockwork points to overdose or inadequate flow.
Cyanobacteria Risk
Carbon dosing with insufficient flow favours cyanobacteria over aerobic heterotrophs. Ensure 30-50x tank turnover and eliminate dead spots before starting. If red slime appears during ramp-up, dose 48 hours of Chemiclean and resume ramping from a lower starting point. See our cyanobacteria treatment chemiclean guide for the treatment protocol.
Skimmer and Oxygen Demand
Bacterial mass doubles the biological oxygen demand of your system. Skimmer pump rating should match or exceed the display volume; a weak skimmer produces murky water within a week of starting carbon dosing. Run an air pump in the sump as insurance during tropical power cuts.
Stopping Carbon Dosing
Taper rather than stop. Halving the dose weekly for a month lets the bacterial population shrink gradually. Abrupt cessation leaves a large population starving, which releases a pulse of bound nutrients back into the water and often triggers algae outbreaks. Align stops with a planned water change for safety margin.
Singapore Tips
NP pellets from Fauna Marin, Two Little Fishies and Reef Interests are stocked along Pasir Ris Farmway shops at $80-120 SGD per 1000 ml. NTUC vodka at 40% ABV works perfectly for dosing if you prefer liquid. Pair with the reef tank icp oes test interpretation workflow to track knock-on effects on trace elements.
Related Reading
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